Fixed

• When a single ConfigCatOptions instance was shared between different clients, they also shared the same Hooks instance. This resulted in inconsistent ready-state handling.
  The type of the ConfigCatOptions's hooks parameter is now a Function(Hooks) instead of Hooks.
  Now, each ConfigCatClient creation creates a new Hooks instance, which is passed to the function set on the options.

Breaking changes

• The type of the ConfigCatOptions's hooks parameter is changed to Function(Hooks).

  Usage is changed from:

  final opts = ConfigCatOptions(
    hooks: Hooks(onFlagEvaluated: (details) => /* handle the event */),
  );

  to:

  final opts = ConfigCatOptions(
    hooks: (h) => h.addOnFlagEvaluated((details) => /* handle the event */),
  );